This invention relates to rotary engines, and, more particularly, to improved means for cooling rotary engines to maintain oil film thickness, thereby reducing wear and extending the useful life of such an engine.
Prior art of possible relevance include the following U.S. Pat. Nos. 3,239,135, issued to Fritz on Mar. 8, 1966; 3,359,615, issued to Bauer Dec. 26, 1967; 3,359,953, issued to Groth on Dec. 26, 1967; and 3,693,608, issued to Neishi on Sept. 26, 1972.
So-called "center housings" of rotary engines have been notoriously difficult to cool due to the fact that heat is generated at localized areas close to the combustion zone without the benefit of at least periodic exposure to a fresh charge of air or a mixture of fuel and air which provides periodic cooling, as is well known in reciprocating engines. Consequently, there is a serious tendency for scuffing, rapid wear and leakage to occur in such areas.
In a like manner, side walls in trochoidal type engines and the spherical outer wall of slant axis rotary engines have a tendency to scuff badly even though such surfaces are rubbed against by seals even with low contact stresses. This is due to the fact that side seals on trochoidal type engines and peripheral seals on slant axis rotary engines move against the surface to be sealed with a large longitudinal component relative to their length in a manner not totally unlike an ice skate on ice. As a consequence, while adequate lubrication may be present at the leading edge of such seals, the leading edge will tend to heat up the surface to be sealed by reason of friction thereby thinning the oil film so that frequently the trailing edge of such a seal is not adequately lubricated and serious scuffing results.
Attempts have been made to overcome these difficulties through structures with improved cooling or replaceable operating chamber liners which may be removed and discarded once badly worn; and the previously identified patents are illustrative of such approaches. While such approaches represent an improvement, they have not proved to be altogether satisfactory.